1. Field of the Invention
The present invention relates to corneal topography slit beam systems. More specifically, the present invention relates to alignment of the slit images obtained from scanning a patient's eye.
2. Description of Related Art
Slit beam systems, such as Bausch & Lomb Incorporated's ORBSCAN II™ topography system are well known in the field of ophthalmology. A slit beam system is described in detail, in the following patents, U.S. Pat. Nos. 5,886,767; 5,512,966; and 6,257,723 all of which are hereby incorporated by reference. Slit beam systems provide a topographical mathematical model or map of a patient's eye. In order to generate the model or map of the eye, the position of the illuminated slit images in three-dimensional space is required. Obviously the more accurately that the position of the slit images is determined, the more accurate the mathematical model will be.
Initial alignment of the eye to the system has always been a serious issue in creating eye models from the image data. Errors in misalignment directly result in errors in both the estimates of optical power and details in the reconstructed eye surfaces, both the anterior corneal surfaces and the posterior corneal surfaces.
It is well known in the art to use half-slit images, which an operator of the slit beam system then manipulates, such that the half-slits are moved to form a single slit image that is centered on the display. This alignment of the half-slit images is used to align the slit beam system to the eye to be measured.
Therefore, if the alignment of the half-slit images could be made to be more accurate, the image data obtained when measuring the eye can then be made more accurate. Errors in the half-slit image alignment directly result in errors in the calculation of the coordinates of the slit images in three-dimensional space.